This invention relates to methods and apparatus for recovering metals from liquid solutions, and in particular to methods and apparatus facilitating to recovery of silver from bleach fix solutions used in photo processing, by disposable cells, at high speed and with high efficiency.
Up to the present time, recovery of conductive metals from solution, and particularly recovery of silver from fixer solutions, has been a relatively expensive process, requiring substantial mechanism and moving parts, as well as close supervision or complex computer controls, to accomplish. This is because the recovery process is electrolytic in nature, and the reaction if not closely monitored can cause sulfiding, damage to the solution and loss of silver. Hence continuous agitation is required as well as close control of the current being supplied to the reaction.
For instance, X-Rite Company offers a number of silver recovery systems, all of which include some type of device provided specifically for agitating the solution. Further, most of the systems offered by X-Rite have a cathode which is coiled, thus having a relatively small surface area.
Similarly, Roconex Corporation manufactures a number of lines of silver recovery systems and markets them under the "Rotex" trademark. All of these systems include some devices specifically devoted to agitation, generally with a rotating cathode which must then be removed from the recovery unit and cleaned, and later reinstalled and reused.
Moreover, all of the systems referred to above are relatively expensive, and there is a need in the marketplace for systems which are less expensive and mechanically simpler, since mechanical simplicity brings with it a high degree of reliability. However, there are also systems that do not provide any agitation, in order to provide the ultimate in simplicity. Since these non-agitating systems may be too slow, some simple means for agitating the solution is called for in a disposable cell recovery process.
This invention relates to improvements to the apparatus described above and to solutions to some of the problems raised thereby.